Humans have 12 pairs of ribs that provide attachments for many muscles of the trunk and protect the internal organs of the thorax. The typical rib consists of a head, neck, and body. The head of the rib articulates with vertebra on the posterior side, attached with joints that allow limited movement for expansion, permitting lung inflation. On the anterior side, they are connected to the sternum (breastbone) by bars of costal cartilage, a type of hyaline cartilage unique to the ribcage, allowing some flexibility or elasticity needed for breathing.
The sternum is a long, narrow flat bone that provides an attachment point for the ribs on the anterior of the body. Structurally it completes the “circle” (actually oval) of the rib cage, providing structural integrity.
